I have just finished googling “78 rpm lp record” and various other combinations of words in the hopes of getting some useful information on mechanical sound recording and playback devices. So far, I have had very little success.
I *have *learned that 78 rpm records were originally pressed in clay, then fired (to make them permanent). They then switched to laquer acetate. I still don’t know how much (timewise) you could record on one side of a 78. I recall that they were 10" in diameter. ISTR some neighbors who had a console record player that could record on wax disks (or possibly something else – I was a kid and assummed it was wax).
Can anyone give me a link or two regarding the history of physical sound recording and playback devices and how they work?
That Prelinger film was interesting. Its neat how, although the level of precision has increased an order or two of magnitude, CDs are mass-produced in much the same process with almost the same terminology (i.e. master, mother, fathers, stampers etc.)
You gotta love how the technicians in the clean rooms all wore vests & ties!
When I was a kid we found a bunch of old 78s in a loft and, um, smashed most of them by throwing them like frisbies into the wall because of the cool way the brittle shelac discs would shatter. Things were probably worth $20 each…
OTTOMH- Big, recordings were of limited length and poor quality. A few years after wire recorders came along, open reel tape machines came along offering longer and better recordings.
As far as I know, no company ever made records out of clay.
The first records were cylinders, invented by Thomas Edison. He originally made them out of tinfoil, then switched to wax (technically it was a metallic soap). The Edison company went through a few different formulations of wax over the years before switching to celluloid.
The first commercially produced flat records were made by the Berliner Gramophone Company in the late 1880s. The first Berliner records were made of zinc, and some of them were produced by etching with a photo-mask (Berliner was trying to get around the Edison patents, which caused the company to use some odd technology).
Most 78 RPM records were made of shellac (actually, shellac was the binder - it was mixed with a lot of other stuff like lampblack). For a long time records were made by recording directly onto a wax platter, which was then metal-plated to produce a master. Lacquer eventually replaced wax as the recording medium. Lacquer was also used to produce instant recordings, such as radio transcriptions.
Edison started producing flat records in 1913. The materials that Edison used changed over the years, but these records were often made of phenolic with a core of compressed wood dust.
A typical 10 inch record would have about three minutes of recorded material on it. Edison records often had as much as five minutes. A twelve-inch 78 could have as much as seven minutes.
There were many types of home recording machines. A lot of them used pre-grooved records made of some type of lacquer or plastic on a rigid core. The core was often made of aluminum.
Not necessarily, unless they’re something rare like old blues & jazz from the 30’s and before. 78’s were produced in such mass quantities and are so durable, that most of them aren’t worth nearly what you’d think these days. (Trust me, I researched this topic very thoroughly when I found a stash of 78’s in my dead uncle’s apartment.)